Glow discharge rectifier with hollow cathodes



1, 1933- I J. NIENHOLD 1,920,660

GLOW DISCHARGE. RECTIFIER WITH HOLLOW CATHODES Filed Dec. 16. 1932 17v vein/Tor? QZI/A Mnfzs MEM/(oL D ATTa/w/ /s.

GLOW DISCHARGE RECTIFIER Patented Aug 1, 1933 WITH HOLLOW CATHODES Johannes Nienhold, Berlin-Charlottenburg, Germany, assignor to Siemens & Halske Aktiengesellschaft,

Siemensstadt, near Berlin, ,Ger-

many, a Corporation of Germany Application December 16, 1932, Serial No. 647,553, k

and in Germany August 27, 1931 1 Claim. (01. 250 -215) given the shape of a' tube intothe two ends of l which the anodes project. It is furthermore Well such a manner that a discharge between them known that a direct discharge between the two anodes can be prevented by placing between them one or several screens preventing a direct passage between the anodes. The drawbacks of such rectifiers consist more particularly in that the cathode fall (the potential drop between the cathode and the anodes). is relatively high and, consequently the efiiciency of the rectifier is very low. i

According to .the invention, a glow, discharge rectifier having at, least two anodes and a subdivided hollow cathode carrying a layer which increases electron emission is constructed so as hollow cathode system completely closed outwardly from a discharge-operative standpoint, in

would only be possible through the hollow oath ode interstices, however, the distance between the cathode surfaces being, however, chosen so as to prevent lines of force from being developed between the anodes. a

A hollow cathode is understood, to be a subdivided cathode in which the different parts are arranged in such a manner and at such a distance apart that the electrons liberated from one portion of the cathode by the impingement of positive ions are propelled into the cathode fall space (region surrounding the cathode in which the potential drop occurs) at the opposite portion of said cathode and are stopped in this fall space,

thus giving rise to a concentration of electrons a cold simple cathode under corresponding con- So far as they cannot be determined ditions. by experiments, these distances may be roughly Mention will therefore only calculated 'bymaking them equal to ten times or twenty times thelength of the mean free gas kinetic electron path. 1 The electron'pathlength 1 within a gas or vapour of a pressure of p millimeters is:

mm 1 V p where 10 is the mean free path of a neutral gaseous molecule, which may be found in chemical tables. For mercury vapour, helium, argon and neon, the values for the electron path'length in millimeters for a pressurefp'of 1 mm. are as follows: i

11g At" Ne Hey A multiplication of these values by from .10 to 20 results in the approximate fall space thickp ness at a gas pressure of 1' mm. 1 to enable two or several anodes to project into a 1 Figs. 1 and 2 show examples constructed ac I cording to the invention: l

Fig. 1 shows an electrode system for a rectifier embodying the invention. The two anodes;

land 2 project into a completely closed hollow cathode system 3. The two leads for the anodes 1 and 2 are shielded from'glow discharge by means .of insulatingftubesA and. 5. The hollow cathode system itself; consists of a metalfenvelope 6 in which there are located superposed metal sheets 7, 8, 9 and 10.. The distanceseparating these sheets. and'the pressure oflthefilling gas have been chosen in such, a manner that direct electrostatic lines of force cannot be developedjbetween the twov anodes 1 and 2,, and, I

consequently, a dischargebetween the anodes j cannot take place. r

Another constructional example is shown. in Fig. 2. Within in a discharge vessel 11,;there are located two re -entrant portions. 12 and 13, carrying the anodes M and 15' which are pro tected from glow' discharge by insulating tubes 16and 17. The two anodes '14 and 15 project 400 into a completely closed cylindrical hollow cathode system 18. The direct connection between 14 and l5'is interrupted by concentrically arranged tubular sheets 19, 20 and 21,. so that direct lines of forcecannot be developed between 5 14 and 15. The lead to the hollow cathode system is'introduced at 22. v

The surfaces of the cathodemetals can be.

vmade of increased electron emissivity in a man ner well-known in the art, for instance by means 1 7 ss f a of barium films on an oxide which'have been'obode and positioned therein'subdividing the 1101- tained from barium azide, BaNs. -In filling these low space between the anodes within the oathtubes, use should preferably be made of rare ode into a plurality of interstices,'the width of 'gasesq p I said interstices being substantially small enough '5 I claim as my invention: 7 .u to' prevent the direct passage of electrostatic, A rectifier of the glow discharge type compris lines of force between said anodes at the pressure ing' an evacuated envelope containing a rarified conditions prevailing within said envelope. atmosphere, a plurality of anodes, a hollow cathv I ode, conductive means forming part of said oath- I J OHANNES NIENHOLD.

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